1. Field of the Invention
The present invention relates to self lubricating binders for use in ceramic extrusion and more particularly to methods for manufacturing a ceramic body wherein the method comprises the use of such novel self-lubricating organic binders.
2. Technical Background
In the formation of ceramic bodies, e.g., silicon carbide, cordierite, mullite, alumina, or aluminum titanate bodies, plasticized mixtures of various inorganic powder batches are prepared which are then formed into various shapes. These plasticized mixtures should be well blended and homogeneous in order for the resulting shaped body to have relatively good integrity in both size and shape, and uniform physical properties. These mixtures typically further comprise organic additives such as binders, plasticizers, surfactants, lubricants, and dispersants as processing aids to enhance cohesion, plasticity, lubricity and/or wetting, and therefore to produce a more uniform batch. In forming processes, such as in extrusion, high pressures must be exerted on both the plasticized batch material and the equipment, e.g., an extrusion die.
Up to the present time, organic binders, such as cellulose ethers, and organic lubricants, such as monocarboxylic acids have been used individually in these batch compositions in order to ensure good batch cohesion and lubrication against the die and other equipment parts, thus insuring longer equipment life, good extruded product quality, and low extrusion pressure. Several of the many U.S. patents that relate to forming ceramic honeycombs by forming batch mixtures containing such raw materials include U.S. Pat. Nos. 4,772,580, 3,885,977, 4,417,908, 5,114,643, and 5,114,644.
However, there still remains an ongoing need to improve upon the ability to provide homogenous plasticized mixtures comprising such binder and lubricant additives in order to improve product quality, and the life of processing equipment. More specifically, increasing the homogeneity of binder and lubricant additives within the plasticized mixtures can provide enhanced lubrication characteristics and thus enable the use of less severe processing conditions and ultimately less expensive processing equipment.